This type of switch device is described in Patent Literature 1, which discloses a conventional example. Such a switch device includes coils provided on each of a switch key top and a switch key bottom. When the switch key top is pressed, a phase of induced current is detected upon production in a coil of the switch key bottom, enabling a switch key top pressing determination to be performed. This type of switch device has merits seen in switch devices that use physical contact, such as the absence of incomplete contact due to contact pin friction or waste adhesion.